CBX7 is involved in the progression of cervical cancer through the ITGβ3/TGFβ1/AKT pathway

The chromobox protein homolog 7 (CBX7) serves a tumor-suppressive role in human malignant neoplasias. The downregulation of CBX7 is associated with the poor prognosis and aggressiveness of various human cancers. However, the biological functions and underlying mechanisms of CBX7 in cervical cancer remain unclear. The present study investigated the role and mechanism of CBX7 in cervical cancer. Lentivirus and siRNA were used to construct cervical cancer cells with stable CBX7 knockdown and SiHa xenograft models. The cell growth, migration, invasion and apoptosis were observed through in vivo and in vitro experiments. The expression levels of CBX7, integrin β3 (ITGβ3), transforming growth factor β1 (TGFβ1), phosphatidylinositol-3-kinase (PI3K), AKT, E-cadherin (E-cad) and vimentin (VIM) were detected by western blot analysis and reverse transcription-quantitative PCR. The correlation between CBX7 and these genes was analyzed. TGFβ1 was also silenced through shRNA in cells with stable CBX7 knockdown to detect its effect on cell growth, invasion and apoptosis, and on pathway-related gene expression. It was revealed that knockdown of CBX7 promoted the proliferation, migration, and invasion of cervical cancer cells, and inhibited apoptosis. In addition, CBX7 knockdown promoted tumor growth in vivo. Correlation analysis demonstrated that CBX7 was negatively correlated with ITGβ3, TGFβ1, PI3K, AKT, phosphorylated AKT and VIM, but positively correlated with E-cad. Moreover, the knockdown of TGFβ1 reversed the promotion of cell proliferation and inhibition of apoptosis induced by CBX7 knockdown and attenuated the increase of ITGβ3, TGFβ1, PI3K, AKT and VIM caused by CBX7 knockdown. In conclusion, the findings of the present study indicated that the downregulation of CBX7 enhances cell migration and invasion while inhibiting cell apoptosis in cervical cancer by modulating the ITGβ3/TGFβ1/AKT signaling pathways.

Expression and correlation analysis of Skp2 and CBX7 in cervical cancer

AIMS

S-phase kinase-associated protein 2 (Skp2) oncoprotein is overexpressed in a variety of cancer tissues and promotes the malignant development of cancer. The expression levels of chromobox homolog 7 (CBX7) protein are varied among different types of cancer tissues, but its role in cervical cancer is not clear. We aimed to examine the expression and clinical significance of Skp2 and CBX7 proteins as well as their correlations in cervical cancer.

METHODS

Immunohistochemistry was used to detect the expression of Skp2 and CBX7 proteins in the cancerous tissues and adjacent tissues of 64 patients with cervical cancer. Relevant clinicopathological data of these patients were collected, compared and analysed for the correlations.

RESULTS

The expression of Skp2 protein in cervical cancer (87.5%) was higher than that in paracancerous tissues (14.1%), and the expression was positively correlated with clinical stage, malignant degree, lymphatic metastasis, vascular invasion and interstitial invasion. The expression of CBX7 protein in cervical cancer (48.4%) was lower than that in paracancerous tissues (96.8%), and the expression was negatively correlated with clinical stage, malignant degree, interstitial invasion, vascular invasion and lymphatic metastasis. The expression of Skp2 protein and CBX7 protein in cervical cancer tissues and adjacent tissues was negatively correlated. The expression of Skp2 and CBX7 proteins was closely related to the clinicopathological features of cervical cancer.

CONCLUSIONS

CBX7 may play the role of a tumour suppressor gene in cervical cancer and provide reference value for the diagnosis and new targeted treatment of cervical cancer.